Control apparatus



p 5, 1962 R. B. MATTHEWS 3,055,418

CONTROL APPARATUS Filed March 25, 1957 INVENTOR. Russell 8. MatthewsAfr): w

United States Patent 3,055,418 CONTROL APPARATUS Russell B. Matthews,Wauwatosa, Wis., assignol', by mesne assignments, to Penn Controls,Inc., Goshen, Ind., a corporation of Indiana Filed Mar. 25, 1957, Ser.No. 648,415

8 Claims. (Cl. 158123) This invention relates to control apparatus andmore particularly to apparatus wherein several control devices areinterlocked to require operation of one of such devices prior tooperation of the other.

More specifically, the present invention pertains to temperature controlapparatus having temperature varying means including control meanstherefor, fan means for circulating air at said temperature varyingmeans, and means interlocking said fan means and the control means forsaid temperature varying means requiring satisfactory operation of saidfan means prior to commencement of operation of said temperature varyingmeans.

It is therefore an object of this invention to provide control apparatushaving two electrically energizable de vices and means interlocking saiddevices to require energization of a given one of such devices prior toenergization of the other.

Another object is to provide control apparatus as characterized abovewherein the first device to be energized is electrically driven fanmeans and the other device is self-powered temperature varying means.

Another object is to provide temperature control apparatus ascharacterized above wherein the self-powered temperature varying meanscomprises a main fuel burner and an ignition burner therefor, and athermoelectric generator responsive to a flame at said ignition burnerto efiect safety shut-01f of said main burner upon outage of theignition burner flame.

Another object is to provide control apparatus as characterized abovewherein the thermoelectric generator comprises at least onesemi-metallic thermoelement.

Another object is to provide in control apparatus having a main fuelburner and fuel flow control means therefor, an electrically driven fanmeans for circulating air at said main burner, a thermoelectricgenerator in circuit with said main burner fuel flow control means andelectroresponsive heating means energized by the source of power forsaid fan means to effect heating of one of the junctions of saidgenerator, whereby said control means is operable to permit fuel fiow tosaid main burner only if there is power available for said fan means.

Another object of this invention is the provision of control apparatuscomprising electrically driven fan means and a source of power therefor,a main fuel burner and an ignition burner therefor, a main burner fuelflow-control device having two cooperating electromagnetic windings, afirst thermoelectric generator in circuit with one of said windings forenergization thereof in response to a flame at said ignition burner, andmeans including a second thermoelectric generator in circuit with theother winding and heating means for one of the thermojunctions of saidsecond generator energized from the source of power for said fan meansto cause said second generator to energize said second winding, wherebyfuel is permitted to flow to said main burner only when a flame existsat said ignition burner and power is available for operation of saidmeans.

Another object is to provide control apparatus as characterized above,including means operatively associated with said first thermoelectricgenerator to cause said first generator to reverse the polarity of itsoutput upon cooling as by outage of the ignition burner flame.

Another object is the provision of control apparatus as characterizedabove wherein the main burner fuel flownine control device is of theelectromagnetic type and wherein said second thermoelectric generatorand its associated electromagnetic winding develop appreciably moreampere-turns than said first thermoelectric generator and its associatedelectromagnetic winding whereby termination of said output of saidsecond generator as by failure of the power source for said fan meanseffects a decrease in the ampere-turns in said flow-control devicesuflicient to cause interruption of main burner fuel flow, there beingmeans associated with said first thermoelectric generator to causereversal of polarity of the output thereof upon cooling and decrease inthe ampere-turns in said flowcontrol device also sufficient to effectinterruption of main burner fuel flow.

The novel features which I consider characteristic of my invention areset forth with particularity in the appended claims. The device itself,however, both as to its organization and mode of operation, togetherwith additional objects and advantages thereof will best be understoodfrom the following description of specific embodiments when read inconnection with the accompanying drawing, in which:

The single figure is a schematic showing of an embodiment of the presentinvention, some of the components of the apparatus being shown insection.

Referring to the drawing, the embodiment selected for illustrationcomprises a fluid flow-control device 8 having a valve body or housing10 formed with an inlet chamber 12 and an outlet chamber 14 connected tocontiguous sections of a main burner fuel supply conduit 16. A partitionwall 18 formed with a valve seat 20 is provided in body It) forseparation of inlet 12 and outlet 14. Conduit 16 extends through asuitable opening in a wall of a heating unit 22 for supply of fuel to amain fuel burner 24 through a mixing chamber 26. Main burner 24 ispositioned within a combustion chamber 28 of heating unit 22, therebeing an exhaust chamber 30 in communication with combustion chamber 28and a bonnet or plenum chamber 32 in heat exchange relation therewith.

A valve operator housing 34 is fixed to control body 10 over an openingin the upper wall thereof, there being a movable partition or flexiblediaphragm 36 fixed therebetween about its marginal edge. Sealing meanssuch as gaskets 38 and 40 are installed on opposite sides of themarginal edge of diaphragm 36 to prevent escape of fluid fuel. Suchpositioning of diaphragm 36 provides a pressure chamber 42 on the sidethereof within housing 34 while the other side thereof is exposed to thefluid pressure at inlet 12.

Fixed to diaphragm 36 by means of a stud 44 and a nut 46 is a controlmember in the form of a valve disc 48 which is movable with diaphragm36' between flowpermitting and flow-preventing positions with respect tovalve seat 20. A back-up plate or reinforcing member 50 overliesdiaphragm 36 and is clamped thereagainst by means including stud 44 andnut 46. Back-up plate 50 functions as a stiffening member for thediaphragm and as a biasing weight for purposes to be hereinafter setforth. Plate 50 also serves to define the effective area of diaphragm 36as is well understood in the art.

Positioned within operator housing 34 on a mounting member 52 is anelectroresponsive valve operator 54 comprising an electromagnet coremember 56 mounted on member 52 and first and second energizable meanssuch as electromagnetic winding 58 and electromagnetic winding 60.Operator 54 further comprises a mounting bracket 62 fixed to member 52and formed with a dished or cup-shaped end portion 62a. An actuating orcontrol member 64 is pivotally mounted with respect to bracket 62 bymeans of a pivot screw 66 formed with a conical end portion 66a forcooperation with the dished end portion 62a of mounting bracket 62.Pivot screw 66 has an end portion 66b formed with a screw driver kerf tofacilitate adjusting the position of screw 66 with respect to lever 64,a lock nut 68 being provided for retaining pivot screw 66 in any desiredposition. A helical tension spring 70 having one end fixed to an extent62b of bracket 62 and its other end fixed to lever 64 is provided tobias lever 64 in a counterclockwise direction about its aforementionedpivot or fulcrum.

Fixed to actuating lever 64 by means of a screw 72 is an armature member74 for cooperation with magnet core member 56 as will hereinafterappear.

A valve member 76 adjustably fixed to actuating lever 64 by means of athreaded valve stem 78 and a cooperating lock nut 80 is provided forflow-control cooperation with a tubular bleed port member 82 threadablyfixed to mounting member 52.

Affording communication between inlet chamber 12 and pressure chamber 42is a fluid passageway 84 formed by aligned openings in valve body 10,diaphragm 36, gaskets 38 and 40, and operator housing 34. A bleedpassage 86 is formed by aligned openings in housing 34 and mountingmember 52 and is afforded communication with the through opening intubular bleed port member 82 by means of a plate 88 sealingly fixed inspaced relation to mounting member 52 by means such as screws 90 andgasket 92. A bleed conduit 94 having communication with bleed passage 86has its free end positioned adjacent main burner 24 within combustionchamber 28. The portions of the pressure chamber above and below themounting member 52 are in free communication as, for example, through anopening 52a in said member.

- Extending through a suitable opening in the side wall of combustionchamber 28 of heating unit 22, is a pilot or ignition burner 96 which,as shown schematically by line 98, is afforded fluid fuel supplyindependently of the aforedescribed control device 8. As is Wellunderstood by those persons skilled in the art, ignition burner 96 ispositioned to afford ignition of main burner 24 and heating of athermoelectric generator 100 positioned within an opening in the sidewall of combustion chamber 28. Generator 100 is so positioned withrespect to combustion chamber 28 as to have one of its thermojunctionsadja cent ignition burner 96 for heating by a flame thereat, and anotherof its thermojunctions outside of combustion chamber 28 to besubstantially independent of temperature changes therewithin.

Thermoelectric generator 100 comprises a pair of thermocouple elementmeans 102 and 104, the latter of which takes the form of an elongatedgenerally cup-shaped sheath member, preferably of stainless steel. Thesheath 104 has a tubular sleeve portion 106 and a tip portion 108. Theopposite end of the member 104 is telescopically received within acounterbore formed in one end of an extension tube 110 of brass orsimilar material and is sealingly fixed therein, as by silver solderingor brazing at 112. The other end of tube 110 is formed with a portion ofreduced diameter to snugly receive one end of a coaxial typethermoelectric generator lead 114 comprising metallic tubular outerconductor i116 and insulated coaxial inner conductor 118. The sleeve 110has an end recess adjacent the lead 114, and said tube and lead aresealingly and electrically connected, for example, by silver solderingor brazing at 120.

The thermocouple element means 102 preferably comprises a rod-like orcylindrical ingot of semi-metallic alloy or composition disposed incoaxial spaced relation Within a sheath 104. Because the thermocoupleelement means 102 is of frangible material, the generator 100 isconstructed in a manner to provide shock resistant mounting meanstherefor. The element means 102 includes a contact electrode 122 havinga stern portion 124 and a shoulder 126. The tube 110 is formed with aninternal annular shoulder 128 and surrounding the contact electrode stemportion 124 is an insulating washer 130 engaging the shoulder 128.Interposed between the insulating washer and the stern shoulder 126 is acompression spring 132 which may take the form of a concave-convexcentrally apertured resilient disc also surrounding the electrode stem124. The sheath 104 is formed with a conical end wall 134, and thesemi-metallic element 102 is formed with a complementary conical endwall 136 which is seated against the end wall 134 to provide athermojunction which hereinafter will be referred to as a hot junction.The spring 132 exerts compressive stresses on the element 102, whichstresses substantially reduce the net tensile stresses to which saidelement is subjected during transverse acceleration or shock, saidcompressive stresses not being so high as to exceed the compressivestrength of said element. The bias of spring 132 also provides thepressure necessary for a satisfactory pressure contact between theelement 102 and the sheath 104 at the hot junction. The pressure typecontact is not deleteriously aifected by deformation of the element 102,for example, on bending under transverse shock, and the conical natureof the surfaces 134 and 136 tends to maintain element 102 in centeredrelationship within the tubular portion 106 of the member 104. Thecompressive stress under which the member 102 is placed increases themagnitude of deformation which said element can withstand withoutfracture and affords the generator 100 substantial shock resistance.

A tube 138 of insulating material preferably surrounds the contactelectrode stem 124, and a flexible conductor 140 extends within the tube138 and affords an electrical connection between the stem 124 and theinner conductor v118 of the coaxial lead 114.

Fixed to the sheath member 104 of generator 100 is a tubular heatconducting member 142 having an inner diameter substantially larger thanthe outer diameter of sheath 104. Tubular member 142 is provided with aninside diameter substantially larger than the outside diameter of sheathmember 104, one end of said member 142 being of reduced size to closelyfit sheath member 104 intermediate the length thereof. Member 142 is ofsufiicient length to prevent a flame at ignition burner 96 from touchingthe sheath 104.

Thermoelectric generator 100 is connected in circuit withelectromagnetic Winding 58 of valve operator 54, the inner conductor 118of coaxial lead 114 being in circuit with a terminal member 144insulatably positioned within a suitable opening formed in operatorhousing 34. One end of winding 58 is connected to terminal member 144while the other end thereof is in circuit with operator housing 34 byelectrical connection thereof to mounting member 52. The outer conductor116 of lead 114 is connected to operator housing 34, a coaxial leadconnector tip (not shown) preferably being threadably secured within asuitably formed receptacle 146 on housing 34 to effect connection of theinner and outer conductors with the various other circuit components.

Positioned adjacent plenum chamber 32 of heating unit 22, is anelectrically driven blower or fan means 150 for circulating the airwithin chamber 32 by forcing the same to the area to be heated by mainburner 24. Connected to electrically driven fan means 150 are lead wires152 and 154 which conduct electrical energy to fan means 150 from asource of alternating current electrical energy schematically shown at156.

Interconnecting the alternating current source at 156 and the controldevice 8, is interlock means comprising a thermoelectric generator 200which is substantially identical with the aforedescribed generator 100.The components of generator 200 which are identical with correspondingcomponents of generator 100 are identified in the drawing with numeralsin the 200 series, the last two digits of each numeral being the same asthe last two digits of the 100 series numeral used to identify the sameor identical component of generator 100. In view of this, it is believedthat reference may readily be made .to the description hereinbet'o-reset forth of generator 1% for all of the components of generator 2011,where- [fore a detailed description of such generator components willnot now be repeated.

A lead wire 3% afiio-rds connection of the inner lead 218 of coaxiallead 214- with a terminal member 302 insul-atably positioned within asuitable opening in housing 34. Other conductor 216 of lead 214 isconnected to housing 34 by means of 1a lead wire 3% having a conditionresponsive switch 306 connected intermediate the length thereof. Leadwires 3% and 304 preferably are inner and outer conductors respectivelyof a coaxial lead, in which event, electrical connection of lead wires3% and 3% with terminal member M12 and housing 34 respectively may bemade through a coaxial lead connector tip (not shown) threadably securedwithin a suitably formed receptacle 308 on housing 34. The electricalcircuit to Winding 60 is completed by connection of one end of saidwinding of to terminal 3G2 and the other end thereof to mounting member52.

The condition responsive switch 3% selected for 11- lustration in thedrawing comprises a stationoary contact 310 fixed to one section of leadwire 3G4 and a bimetal element 312 connected to the other section oflead wire 304, and carrying a movable contact 3 14 for circuitcontrolling cooperation with stationary contact T110 upon deformation ofbimetal element 312 with changes in ambient temperature lthereat. Iprefer to locate switch 306 in the space or area to be alforded heat bymain burner 24 so as to provide thermostatic control as will hereinafterappear.

Fixedly positioned on sheath member 2% of thermoelectric generator 200,is an electroresponsivc temperature affording device 316 comprising anelectric heating coil 318 for varying the temperature of the generatorthermojunction afforded by conical surfaces 234 and 236. One end of coil318 is connected to lead wire 152 and the other end of coil 318 isconnected to lead wire 15 1, thereby placing said coil 31S directly incircuit with the source of v iternating current shown at 156.

In order to obtain optimum operation of the appara tus *hereinbeforedescribed, I prefer to construct thermoelements 102 and 2 ofthermoelectric generators 1th and 2th) respectively in a particularmanner. That is, either or both of elements 1&2 and 20 2 may, forexample, be formed of an alloy described in the Robert W. Fritts andSebastian Karrer Patent No. 2,811,571.

Mechanical and electrical contact between the thermocouple elements 164and 204, and the semi-metallic thermocouple elements 102 and 292,respectively, is made over a substantial area by the pressure contactbetween the surfaces 134 and 136 and between the surfaces 234 and 236respectively. Contact with the opposite ends of the elements 162 and 2&2is made over substantial areas thereof to the contact electrodes 122 and222. Such contact electrodes provide contacts of low thermal andelectric resistance, and are chemically stable with respect to theelements 102 and 202. As more fully described in Russell E. Frederick,Robert W. Fritts and William V. Huck Patent No. 2,811,569, iron isespecially adapted for use as contact electrode material withlead-telluriumselenium compositions.

It will be noted that when the tips 168 and 2418 of the sheaths 104- and2114 are heated, the elements 102 and 2&2 are free to expand and theflexible conductors Mil and 240 maintain continuity of the respectiveelectrical circuits between the electrodes 1 22 and 222 and the leadconductors 118 and 218 while at the same time affording means forisolating said electrodes and the elements 102 and 2412 from externalforces which might be applied to the leads 114 and 214.

Since, as is well known in the ant, the electrical and thermalresistance of the thermoelectrical generators are dependent upon theconfiguration thereof, as well as on the electrical and thermalconductivities of the elements 102 and 202 and sheaths 104 and 204, arelationship be tween the dimensions of the elements and sheaths can beobtained which affords the highest thermal conversion efliciency in sucha mounting or assembly. In the embodiments described, the thermalconductivity of the elements 1112 and 202 is low as compared with thatof the elements 104 and 264 (for example, .02 w./cm./ C. as compared to.261 w./cm./ C.).

For elements of any given thermal and electrical conductivities theconversion efiiciency depends strongly upon the ratio of thickness ofthe sheath to the radius of the element or more specifically upon thecross-sectional area of the two. In the embodiments illustrated, thisratio of the radius of the elements 102 and 202 to the thickness of thesheaths 104 and 204 is preferably about 6 to l or more.

t is understood, of course, that the conversion elficiency of thethermocouple is also dependent upon the difference between the hot andcold junction temperatures. For thermocouples utilizing a semi-metallicinner element, having a low thermal conductivity, high temperaturedifferences can be achieved by selecting for the semimetallic element aratio of length to diameter, which in the exemplary embodiments hereindisclosed is about 4 to 1, such that radiation transfer of heat from thesurface of the inner element to the sheath establishes substantialtemperature gradients within the inner element, particularly near thehot junction. When this is done, the heat flow into the inner elementthrough the hot junction, i.e., the juncture of the conical faces isexhausted to the case over the entire side wall surface of the innerelement allowing the inner cold junction, i.e., the juncture of theelement with the contact electrode, to assume a temperature onlyslightly greater than that of the outer cold junction, i.e., thejuncture of the sheath and sleeve. A further consequence of suchradiative cooling is the reduced electrical resistance of thesemi-metallic elements, said elements having a positive temperaturecoefilcient of resistance.

The radiation responsible for the removal of the heat transmitted acrossthe hot junction takes place between the element, its cold junctionelectrode, and the metal walls of the sheath and extension tube.

The operation of the control apparatus shown in the drawings will now bedescribed:

As shown, pilot burner 96 is alforded fuel flow independently of controldevice 8 and provides a flame in heating relation to thermoelectricgenerator and main burner 24. Also, electrically driven fan means iscontinuously energized from the source of alternating current electricalenergy at 156, although, as will be readily apparent to those personsskilled in the art, switch means may be provided in circuit therewith toprovide the desired control. In any event, it is necessary that thepilot burner 96 be ignited and the alternating current source shown at156 be operable to afford energization of fan means 150 beforeflow-control device 8 will permit fuel flow to main burner 24 as willhereinafter become apparent as the description of the operation of thecontrol apparatus proceeds.

The flame at ignition burner 96 effects heating of the hot junction ofgenerator 160 thereby effecting energization of winding 58 ofelectromagnetic valve operator 54 through a circuit comprising innerconductor 118 of coaxial lead 114, terminal member 144, winding 58,mounting member 52, operator housing 34 and outer conductor 116 of lead114. The number of turns of wire and the diameter of the Wire of whichwinding 58 is constructed must be determined, in accordance with thepredetermined normal direct current output of generator 100 in responseto heating of the hot junction thereof by the flame at ignition burner96, so that the ampere-turns resulting in magnet core 56 by virtue ofenergization of winding 58 by generator 100 is less than a first orpull-in level necessary to attract armature 74 against the biasing forceof spring 70 and is also less than a predetermined lower second ordrop-out level below which said energization is insufficient to hold thearmature in attracted position when moved thereto. Under theseconditions, it is seen that bleed port valve member 76 remains inflowpreventing engagement with bleed port member 82 thus permitting thefluid pressure within pressure chamber 42 to equal the fluid pressure atinlet 12 of valve body by virtue of passageway 84. Since the pressurewithin chamber 42 acts upon the entire surface of reinforcing back-upplate 50 and whereas the fluid pressure at inlet 12 acts upon only aportion of the under side of valve disc 48, said valve disc 48 isretained in flow-preventing engagement with valve seat 20.

In order to move valve disc 48 to its flow-permitting position, it isnecessary that electromagnetic winding 69 of valve operator 54 beenergized concurrently with the aforementioned energization ofelectromagnetic winding 58. This requires two additional conditions.Firstly, it is necessary that the alternating current source shown at156 effects energization of heating coil 318 of temperature varyingmeans 316 so as to heat the hot junction of generator 200 for generationof a predetermined normal electrical potential by the latter. Secondly,it is necessary that thermostatic switch 306 respond to a giventemperature condition so as to effect engagement of movable contact 314and stationary contact 310 so that the normal electrical potentialgenerated by generator 200 causes current to flow through winding 60 byvirtue of the electrical circuit comprising inner conductor 218 ofcoaxial lead 214, lead wire 300, terminal 302, winding 60, mountingmember 52, operator housing 34, lead Wire 304 including thermostaticswitch 306 and outer conductor 216 of lead 214. Such energization ofwinding 60 affords suflicient magnetic flux flow within magnet core 56which when combined with the magnetic flux flow therein resulting fromenergization of winding 58 affords a total number of ampere-turns at orabove said first or pull-in level for movement of the armature member 74into attracted relation with respect to core member 56 against thebiasing force of tension spring 70.

Such attractive movement of armature member 74 effects movement of bleedvalve 76 to its flow-permitting position by virtue of clockwise pivotalmovement of actuating lever 64 about the fulcrum or pivot point betweenbracket 62 and screw 66. Such movement of bleed valve member 76 permitsthe fluid pressure within pressure chamber 42 to diminish by reason offluid flow from chamber 42 to combustion chamber 28 of heating unit 22through the opening in bleed port member 82, the passageway betweenmounting member 52 and member 88 spaced therefrom, passageway 86, andbleed conduit 94, Such diminution of fluid pressure within chamber 42continues until a point is reached where the total pressure on the uppersurface of back-up plate 50 is insufficient to retain valve disc 48 inits flow-preventing position against the total force exerted on theunder side of valve disc 48 by the fluid pressure at inlet 12. When thispoint is reached, the inlet pressure forces valve member 48 to itsflow-permitting position, whereupon fluid fuel is permitted to flow tomain burner 24 from inlet chamber 12, through valve seat 20, outletchamber 14, main burner fuel supply conduit 16 and mixing chamber 26.The fluid fuel thus emitted at main burner 24 is ignited by the flame atignition burner 96.

Burning of fuel at main burner 24 causes heating of the air withincombustion chamber 28, the products of combustion being exhaustedthrough exhaust chamber 30 and appropriate exhaust conduits. Sinceplenum chamber 32 is in heat exchange relation with combustion chamber28 and exhaust chamber 30, the air within plenum chamber 32 increases intemperature and is forced to the area or space to be heated by means ofthe previously energized electrically driven fan means 158 which ispositioned adjacent plenum chamber 32.

Thus, the air within the area or space to be heated by main burner 24increases in temperature until the birnetal 312 of thermostatic switch306 (positioned within such area or space) deforms sufliciently toeffect disengagement of movable contact 314 and stationary contact 318.'In such event, electromagnetic winding 60 is immediately deenergized,the magnetic flux flow afforded thereby within core member 56 beingterminated. With electromagnetic winding 58 thus being the only windingaffording magnetic flux flow in magnetic core 56, said flux flow dropsto or below said lower or drop-out value and the tension spring 70overcomes the magnetic attraction between armature member 74 and coremember 56 for counterclockwise pivotal movement of actuating lever 64about its aforementioned fulcrum. In this manner, bleed valve 76 isreturned to its flow-preventing position in engagement with bleed portmember 82. Such movement of bleed valve 76 interrupts further bleedingof the fluid pressure within pressure chamber 42 whereupon the pressureon back-up plate 50 is permitted to increase. Pressure continues toincrease until a point is reached where the total force on back-up plate50 is sufiicient to overcome the force tending to retain valve disc 48in its flow-permitting position, whereupon said valve disc 48 is movedto its flow-preventing position in engagement with valve seat 20 and isheld in such position by virtue of the fluid pressure within chamber 42as provided from inlet chamber 12 through passageway 84.

It may occur, that heating coil 318 is deenergized as by failure of thesource of alternating current at 156 or by interruption of theenergizing circuit for said winding 318. Under either of theseconditions, heating of the hot junction of thermoelectric generator 208will be interrupted and said generator 288 will no longer be able togenerate the electrical potential which affords current flow throughelectromagnetic winding 60 as hereinbefore explained. If contacts 314and 310 of thermostatic switch 306 are in engagement at this time,electromagnetic winding 60 is deenergized and the fuel flow to mainburner 24 terminated as above set forth. In order for such operation totake place, it is necessary that deenergization of the winding 60decrease the magnetic flux flow in core member 56 to or below saiddrop-out value. With present day devices, such drop-out value isgenerally in the neighborhood of one-half the pull-in value. In order toattain this relationship, I prefer to select the wire size and number ofturns for each of the windings 58 and 60 such that the ampere-turnsratio of such windings when energized by the normal output of generatorsand 200, respectively, is approximately 1.5 to 2.0 with winding 60producing the greater number of ampere-turns. Under these normalconditions energization of both of the windings 58 and 60 producessufficient ampere-turns, for example 3.5X ampere-turns to attractarmature member 74 into engagement with core member 56 against thebiasing force of spring 70, Whereas, deenergization of only winding 60decreases the total ampere-turns in core member 56 to somethiing lessthan one-half of the ampere-turns utilized for attracting the armature,for example to 1.5X ampere-turns, whereupon spring '70 overcomes theremaining attractive force between armature 74 and core member 53, asproduced by energization of only winding 58, for return of bleed portvalve member 76 into flow-preventing engagement with bleed port member82.

Should heating coil 318 be deenergized while contacts 310 and 314 aredisengaged, said winding 60 will not be reenergized upon subsequentreengagement of contacts 314 and 310 wherefore sufficient magnetic fluxflow in magnet member 56 will not be produced by energization of onlywinding 58 to move armature 74 into engagement with core member 56 and,hence, fuel will not be permitted to flow to main burner 24 uponreengagement of contacts 314 and 310 until the cause of failure of thealternating current source or the break in the energizing circuit forheating coil 318 is rectified.

It will be noted that the above'explained coordination requires that theenergizing source for fan means 150 and the circuit associated therewithbe in proper operating condition so that the heated air within plenumchamber 32, as afforded by main burner 24, will not be permitted toaccumulate therein and create a hazardous condition. This arrangement isparticularly desirable in those heating units which depend substantiallysolely upon electrically operated means for moving the air from theplenum chamber after it is heated by the main burner.

Should the flame at ignition burner 96 be extinguished for any reason,the hot junction of generator 100 will cool to a point where saidgenerator 100 is incapable of generating the aforedescribed normalelectrical potential for energization of electromagnetic winding 58 ofbleed port operator 54. However, since winding, 58 when energized,produces less magnetic flux flow in core member 56 than does winding 60when it is energized (ratio of 1.5 to 2.0 as above explained) it is seenthat if winding 53 is deenergized, as :by pilot flame outage, Whilearmature '74 is in attracted position, as by simultaneous energizationof both of the windings 58 and 60, the resulting loss of magnetic fluxflow in core member 56, for example to 2.0X ampere-turns is insufiicientto cause spring 70 to return bleed port valve 76 to its flow-preventingposition. As above explained, this is due to the fact that the drop-outenergization of present day devices is generally in the neighborhood ofone-half the pull-in energization, for example 1.75X ampere-turns.

In view of this, I employ the tubular heat conducting member M2 ongenerator 106* to reverse the polarity of energization of winding 58 bysaid generator me upon outage of the flame at pilot burner 96. Uponoutage of the pilot flame, not only is the temperature of the hot andcold thermojunctions of generator 100 eventually equalized, but due tothe placement of tubular member 142 on sheath member 102 with respect tothe hot and cold junctions of the generator, the relative temperaturesthereof are reversed due to the particular heat conduction by saidtubular member 142. 142 shields the hot junction somewhat from the heatof the flame of the pilot burner flame, whereas heat from said flame istransferred by said member to the areas of the cold junctions of thethermoelements 162 and 104, which areas store substantial heat. Onoutage of the pilot burner 96, the impingement of the unignited gas onthe hot junction, and the relatively lower heat capacity of the hotjunctions as compared with the cold junctions, causes rapid cooling ofthe hot junction as compared with slow cooling of the cold junctions,with resultant current reversal. In this manner, winding 58 is reverselyenergized so as to produce magnetic flux flow in core member 56 whichbucks or opposes the magnetic flux flow therein as produced byenergization of winding 60, whereupon the resultant magnetic flux flowin said core 56 is reduced to or below the predetermined lower ordropout value which is something less than one-half the flux flowrequired for pull-in of the armature 74, for example to 1.25Xampere-turns and spring 70 operates to return bleed port valve 76 in itsflow-preventing position in engagement wtih bleed port member 82. Thusthe present control apparatus affords, safety shut off of fuel flow tomain burner 24 upon outage of the pilot burner flame.

Should the pilot flame become extinguished while winding 60 isdeenergized as by appropriate response of thermostatic switch 306, bleedport valve 76 will not be moved to flow-permitting position uponsubsequent reengagement of cont-acts 314 and 310 of switch 306 since themagnetic flux flow produced in core 56 by energization of only winding60- will be something less than the pullin value of energization ofelectromagnetic operator 54.

In view of the foregoing, it is seen that the present invention providescontrol apparatus employing novel thermoelectric generator means in aparticular manner whereby fuel flow to a main fuel burner is dependentIn operation, the member 10 7, upon the presence of a pilot burner flameand satisfactory operation of an outside source of power and associatedcircuit means; said source of power being used for energization ofelectroresponsive means associated with said main fuel burner.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the spirit of theappended claim-s.

I claim:

1. Control apparatus comprising an electroresponsive operator having acontrol member movable between first and second positions and havingmeans biasing the same toward said second position, said control memberbeing movable against said biasing means toward said first position byenergization of said operator above a predetermined first level andbeing movable by said biasing means toward said second position wheneverenergization of said operator is at or less than a predetermined lowerlevel, a source of alternating current, a first source of direct currentof predetermined normal magnitude operatively related to saidalternating current source and continuously operable simultaneouslytherewith, and a second source of direct current of predetermined normalmagnitude, said first and second direct current sources being connectedto energize said operator and normally operable concurrently to affordenergization thereof above said first level for disposition of saidcontrol member in said first position, said first source being normallyoperable individually to afford energization of said operator above saidlower level, and said second source being normally operable individuallyto at most atford energization of said operator at less than said lowerlevel, said second source being reversible to oppose the energization ofsaid operator afforded by said first source at least sufficiently toreduce the effective energization of said operator normally afforded bysaid first source to below said lower level for disposition of saidcontrol member in said second position.

2. Control apparatus comprising an electroresponsive operator having acontrol member movable between first and second positions and havingmeans biasing the same toward said second position, said control memberbeing movable against said biasing means toward said first position byenergization of said operator above a predetermined first level andbeing movable by said biasing means toward said second position wheneverenergization of said operator is at or less than a predetermined lowerlevel, a source of alternating current, a first source of direct currentof predetermined normal magnitude operatively related to saidalternating current source and continuously operable simultaneouslytherewith, a second source of direct current of predetermined normalmagnitude, said first and second direct current sources being connectedto energize said operator and normally operable concurrently to affordenergization thereof above said first level for disposition of saidcontrol member in said first position, said first source being normallyoperable individually to alford energization of said operator above saidlower level, and said second source being normally operable individuallyto at most afford energization of said operator at less than said lowerlevel, said second source being reversible to oppose the energization ofsaid operator afforded by said first source at least sufficiently toreduce the effective energization of said opera tor normally aiforded bysaid first source to below said lower level for disposition of saidcontrol member in said second position, and circuit controlling means incircuit with said first source and said operator for controlling theenergization of said operator by said first source and thereby thedisposition of said control member.

3. Control apparatus for use with fuel burning equipment having a burnercomprising an electroresponsive operator having a control member movablebetween first and second positions and having means biasing the sametoward said second position, said control member being movable againstsaid biasing means toward said first posi tion by energization of saidoperator above a predetermined first level and being movable by saidbiasing means toward said second position whenever energization of saidoperator is at or less than a predetermined lower level, a source ofalternating current, a first thermoelectric generator having athermojunction, a heater connected in continuously closed circuit withsaid alternating current source and continuously energized by currentfrom said source and disposed in heating relation to said thermojunctionto render said generator continuously operative to generate directcurrent of predetermined normal magnitude, a second thermoelectricgenerator of predetermined normal output, said first and secondgenerators being connected to energize said operator and being normallyoperable concurrently to afford energization thereof above said firstlevel for disposition of said control member in said first position,said first generator being normally operable individually to affordenergization of said operator above said lower level, and said secondgenerator being normally operable individually to at most affordenergization of said operator at less than said lower level, said secondgenerator having means associated therewith to render the polarity ofthe output thereof reversible to oppose the energization afforded bysaid first generator at least sufficiently to reduce the effectiveenergization of said operator to below said lower level for dispositionof said control member in said second position.

4. Control apparatus for use with fuel burning equipment having a burnercomprising an electroresponsive operator having a control member movablebetween first and second positions and having means biasing the sametoward said second position, said control member being movable againstsaid biasing means toward said first position by energization of saidoperator above a predetermined first level and being movable by saidbiasing means toward said second position whenever energization of saidoperator is at or less than a predetermined lower level, a first sourceof direct current of predetermined normal magnitude, and a second sourceof direct current responsive to the flame of said burner to normallyafford direct current of predetermined magnitude and of one polarity andupon outage of said flame to afford direct current of the oppositepolarity, said first and second direct current sources being connectedto energize said operator and normally operable concurrently during theexistence of a flame at said burner to afford energization of saidoperator above said first level for disposition of said control memberin said first position, said first source being normally operableindividually to afford energization of said operator above said lowerlevel, and said second source being normally operable individuallyduring existence of a flame at said burner to at most affordenergization of said operator at less than said lower level, said secondsource, on outage of said burner flame, affording a current of saidopposite polarity which opposes the energization of said operatornormally afforded by said first source at least sufficiently to reducethe effective energization of said operator to below said lower levelfor disposition of said control member in said second position.

5. Control apparatus for fluid fuel burning equipment having a mainburner and a pilot burner comprising a main burner fuel valve having anelectroresponsive operator and a valve member movable between open andclosed positions and having means biasing the same toward closedposition, said valve member being movable against the bias of saidbiasing means toward open position by energization of said operatorabove a predetermined first level and being movable by said biasingmeans toward closed position whenever energization of said operator isat or less than a predetermined lower level, a first source of directcurrent of predetermined normal magnitude, and

a second source of direct current responsive to the flame of said pilotburner to afford direct current of predetermined normal magnitude and ofone polarity and upon outage of said pilot burner flame to afford directcurrent of the opposite polarity, said first and second direct currentsources being connected to energize said operator and normally operableconcurrently during the existence of a flame at said pilot burner toafford energization of said operator above said first level fordisposition of said valve member in said open position and flow of fuelto said main burner, said first source being normally operableindividually to afford energization of said operator above said lowerlevel, and said second source being normally operable individuallyduring existence of a flame at said pilot burner to at most affordenergization of said operator at less than said lower level, said secondsource, on outage of said pilot burner flame, affording a current ofsaid opposite polarity which opposes the energization of said operatornormally afforded by said first source at least sufliciently to reducethe effective energization of said operator to below said lower levelfor disposition of said valve member in said closed position and shutoff of the fuel to said main burner.

6. Control apparatus for fluid fuel burning equipment having a mainburner and a pilot burner comprising a main burner fuel valve having anelectroresponsive operator and a valve member movable between open andclosed positions and having means biasing the same toward closedposition, said valve member being movable against the bias of saidbiasing means toward open position by energization of said operatorabove a predetermined first level and being movable by said biasingmeans toward closed position whenever energization of said operator isat or less than a predetermined lower level, a source of alternatingcurrent, a first thermoelectric generator having a thermojunction, aheater connected in continuously closed circuit with said alternatingcurrent source and continuously energized by current from said sourceand disposed in heating relation to said thermojunction to render saidgenerator continuously operative to generate direct current ofpredetermined normal magnitude, and a second thermoelectric generatorresponsive to the flame of said pilot burner to afford direct current ofpredetermined normal magnitude and of one polarity and having meansassociated therewith to render the polarity of the output thereofreversible upon outage of said pilot burner flame to afford directcurrent of the opposite polarity, said first and second generators beingconnected to energize said operator and being normally operableconcurrently during the existence of a flame at said pilot burner toafford energization of said operator above said first level fordisposition of said valve member in said open position and flow of fuelto said main burner, said first generator being normally operableindividually to afford energization of said operator above said lowerlevel, and said second generator being normally operable individuallyduring existence of a flame at said pilot burner to at most affordenergization of said operator at less than said lower level, said secondgenerator, on outage of said pilot burner flame, affording a current ofsaid opposite polarity which opposes the energization of said operatornormally afforded by said first generator at least sufficiently toreduce the effective energization of said operator to below said lowerlevel for disposition of said valve member in said closed position andshut off of the fuel to said main burner.

7. Fuel burning apparatus having a burner comprising a fuel valve forsaid burner having an electroresponsive operator having a control membermovable between flow permitting and flow preventing positions and havingmeans biasing the same toward flow preventing position, said controlmember being movable against said biasing means toward flow permittingposition by energization of said operator above a predetermined firstlevel and being movable by said biasing means toward flow preventingposition whenever energization of said operator is at or less than apredetermined lower level, a source of alternating current, an aircirculating fan connected for energization by said alternating currentsource, a first source of direct current of predetermined normalmagnitude operatively related to said alternating current source andcontinuously operable simultaneously therewith, and a second source ofdirect current of predetermined normal magnitude, said first and seconddirect current sources being connected to energize said operator andnormally operable concurrently to afford energization thereof above saidfirst level for disposition of said control member in said flowpermitting position, said first source being normally operableindividually to afford energization of said operator above said lowerlevel, and said second source being normally operable individually to atmost afford energization of said operator at less than said lower level,said second source being reversible to oppose the energization of saidoperator afiorded by said first source at least suificiently to reducethe efiective energization of said operator normally afiorded by saidfirst source to below said lower level for disposition of said controlmember in said flow preventing position, failure of said alternatingcurrent source effecting failure of said first direct current source andmovement of said control member to flow preventing position for shut-01fof the fuel flow to said burner substantially simultaneously withde-energization of said circulating fan.

8. Control apparatus comprising an electroresponsive operator havingfirst and second windings and having a control member movable betweenfirst and second positions and having means biasing the same toward saidsecond position, said control member being movable against said biasingmeans toward said first position by energization of said operator abovea predetermined first level and being movable by said biasing meanstoward said second position whenever energization of said operator is ator less than a predetermined lower level, and first and second sourcesof direct current connected to energize said first and second windingsrespectively and having predetermined diiferent normal output, saidsources being operable concurrently to energize said windings andaflford said operator energization above said first level fordisposition of said control member in said first position, said firstsource and first winding being normally operable independently of saidsecond source and second winding to afford energization of said operatorabove said lower level, and said second source and second winding beingnormally operable independently of said first source and first windingto at most afiord energization of said operator at less than said lowerlevel, the polarity of the direct current supplied by said second sourcebeing reversible to cause energization of said second winding by directcurrent of said reverse polarity in opposition to the energization ofsaid operator afforded by said first source and first winding at leastsufficiently to reduce the eifective energization of said operator tobelow said lower level for disposition of said control member in saidsecond position.

References Cited in the file of this patent UNITED STATES PATENTS2,265,294 Lange Dec. 9, 1941 2,290,047 Hildebrecht July 14, 19422,437,894 Ray Mar. 16, 1948 2,464,945 Rouse Mar. 22, 1949 2,676,757Thornbery Apr. 27, 1954 2,710,056 Parrett June 7, 1955

